What If You Only Sometimes Work Out?

It’s pretty common to have an on-again, off-again relationship with exercise. But isn’t working out sometimes better than not working out at all?

Mostly, yes.

New thinking from exercise scientists suggests that occasional exercise still benefits the body, even if it’s inconsistent. Studies from the last few years have shown that people who cram their weekly exercise into one or two days on the weekend — so-called “weekend warriors” — can make up for a week of sloth. “If you choose to exercise only on the weekends and equal the volume of someone exercising three days a week during the week, you get the same health benefits,” says Linda Pescatello, PhD, a kinesiology professor at the University of Connecticut.

The body changes quickly with exercise. Within weeks, cardiovascular endurance and flexibility improve and activity feels easier as the body becomes more efficient at breathing and regulating oxygen, says Melissa Morris, a certified exercise physiologist and educator. “Individuals may also notice some fat loss and muscle gain within four to six weeks,” she says, along with lower blood pressure, better mental health, and more energy. These improvements continually increase as people remain active, though they may eventually slow or even plateau.

There are instantaneous benefits as well. For example, studies have shown that after a brisk walk, blood pressure lowers and may remain lowered throughout the day, Pescatello says. “With blood pressure, glucose, insulin, and some components of the blood lipid profile, exercise clearly has acute and immediate health benefits.”

But once a person stops exercising, those changes can disappear just as fast. Morris says that deconditioning occurs anywhere from one to four weeks after exercise is stopped, depending on the person’s fitness level (the more fit you are, the longer it takes the body to decondition). Cardio endurance begins to decline first, followed by muscular fitness.

“People used to think you weren’t getting any benefit if you didn’t at least exercise for 10 minutes. That’s not true. Any amount accumulated throughout the day is beneficial.”

“Most cardiorespiratory endurance will be gone in three to four weeks,” Morris says. “Muscular strength and muscular endurance are slower to decline, taking six weeks or more. It can take up to 12 months to lose all the muscular fitness gained from a regular exercise program.”

What happens when this routine becomes cyclical?

When you’re not consistently working out, your body fluctuates back and forth between gaining and losing health benefits and fitness levels. The good news is, past exercise routines make it easier to bounce back after not exercising for a while. “One thing that does happen with exercise, even with irregular exercise, is called muscle memory,” Morris says. “You train your muscles to remember a movement and even though muscles may shrink with less activity, the muscle cells are still there.”

The issue is trickier if people are using exercise as part of a weight-loss plan. One study found that weight gained during a break from exercise may be harder to work off when exercise begins again. The researchers studied the data of 29,835 runners and found that those who gained weight when they stopped or reduced their mileage had a harder time losing that weight again when they resumed running.

Some of that problem comes from eating habits that don’t change alongside the workouts. “Most people tend to eat back the calories that they burned through exercise,” Morris says. “So if you stop exercising, but don’t change your eating too, then weight gain is much easier.”

But overall, any negative effects of inconsistent workouts are countered by the benefits exercise can bring. Regular exercise is best, but change can happen fast, even if the physical activity is low intensity or occasional.

And remember: A consistent workout routine doesn’t have to mean a three-mile run every day. “People used to think you weren’t getting any benefit if you didn’t at least exercise for 10 minutes [at a time],” Pescatello says. “That’s not true. Any amount accumulated throughout the day is beneficial. Even though you don’t have time to do your three-mile run, try to find time for walking more during your day, and you can accumulate your exercise throughout the day.”